Process for dyeing acrylonitrile textile with copper salt and furfural



PROCESS FOR DYEING ACRYLON'ITREE TEX- TILE WITH COPPERS ALT AND- Joseph. John Iannarone, In, Penns'Grove, -N. J,., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del.,.a corporation. ofDelaware No Drawing. Application March 22, 1952, Serial No. 278,120

Claims. (Cl. 8-55) This invention relates to a chemical process. More specifically, it relates to a process for dyeing a textile produced from a polymer of acrylonitrile.

By the term textile nitrile is meant a filament or fiber or the like formed by extrusion of a polymer of .acrylonitrile. such .as. is illustrated in U. S. Patent, No. 2,436,926 to R. A. Jacobson dated March 2, 194.8,v audalso the yarn, staple, fabricand the like produced therefrom. The term polymer .of acrylonitrile is intended to. include any polymerof acrylonitrile, including polyacrylonitrile (i. e., the homopolymer), wherein the acrylonitrile component constitutes about 40% or more of the polymer molecule calculated as CH2: HCN. Among the compounds that may be copolymerized with acrylonitrile may be mentioned vinyl chloride, 2-vinyl pyridine, 4-vinyl pyridine, 5-ethyl-2- vinyl pyridine and 2- or 4-v.inyl quinoline. Such copolymeric materials are shown in U. S. Patent No. 2,491,471 to H. W. Arnold dated December 20, 1949. Other materials, such as plasticizers and modifiers, may also be present.

Due to inherent characteristics of textiles which are produced from a polymer ofacrylonitrile, great difliculty' has been experienced in dyeing them by conventional procedures. The most satisfactory method developed thus far is considered to be that known as the cuprous ion technique, as is described in Chemical and Engineering News 28, 4268 (1950).. According to this procedure, dyes, generally known as acid wooldyes, areapplied from an aqueous solution containing cuprous ions produced from copper salts by means of sodium formaldehydesulfoxylate or zinc formaldehydersulfoxylate. In this method it has been diflicult, and in most cases impossible, to prevent the precipitation of rnetalliccopper, especially when short baths are used, that is, where the ratio of the weight of dyebath to the weight of the fiber is :1 to 20: 1. Even when longer baths are employed, the cuprous oxygen of the air to .thecupric ion which is inefiective for dyeing. The problem is particularly acute in the dyeing of highly-drawn textiles produced from a polymerof acrylonitrile. The dyeing of .these materials requires temperatures considerably in excess of 212 F. Under these conditions, the problems of he cuprous ion procedure, as outlined above, are particularly acute.

It is an object of the present invention to provide a novel process for the dyeing of a textile produced from a polymer of acrylonitrile with acid wool dyes.

Another object is to provide an improved process for the dyeing of a textile produced from a polymer of acrylonitrile with an acid Wool dye, employing a modified cuprous ion technique.

A further object is to provide a novel and improved process for the dyeing of a highly-drawn textile produced from a polymer of acrylonitrile in strong, level shades, employing a modified cuprous ion technique.

These and other objects will become apparent in the course of the following specification and claims.

In accordance with the present invention, it has been from aqueous baths, under pressure, at temperatures considerably (i. e., at least about 10 F.) in excess of 212 F., within a pH range of about 1.5 to 5 in the presence of copper salts in amounts sufiicient to provide 0.5 to 2.5 weight percent ofcuprous ion and from about 1% to produced from a polymer ofaerylo 2,700,589 Y Patented Jan. 25, 1955 10% of furfural (both based on the weight of the. fiber to be dyed) using acid wool dyes.

The following mples are. cited y way of illustration and are not intended to limit the invention in any manner.

EXAMPLE I A one-pound package of polyacrylonitrilesewing thread having a draw ratio of 8x (i. e., the drawn length is eight tunes that of the undrawn culating machine adapted for bath composition is as follows:

1.5% of the red acid dye of .C. I. 176- 1'0.0% furfural 6.0% copper sulfate-SHhO 5.0% sulfuric acid The furfural is added to a. solutionof copper sulfate in 1 liter of water. This solution is then placed in the expansion tank of the circulating machine. The sulfuric acid is added. The water content is increased to facilitate circulation (to about 4 liters total liquids). The temperature s raised to 180 F. The red dye (dissolved inabout 0.5 liter of water) is added. The bath -is heated to a. temperature of 250 E, which temperature is maintained for 1 hour. The package is then rinsed, soaped and dried. It 1s observed to be of an even, clear red shade.

EXAMPLE 2 Example 1 is repeated with a dyebath having a composition as follows:

The package is observed to be of a clear, level, bright pink shade.

length) is; dyed; in. .a cirpressure work. The dye- EXAMPLE 3 A one-pound package of polyacrylonitn'le fiber stock havmg a draw ratio of 8X Iis .dyed in a circulating machine adapted for pressure employing a dyebath of the following composition:

1.3% of sodium 2-sulfonate 0.9% of the yellow quinoline dye of C. I. 802

6.0% copper sulfate-SHzO 10.0%furfural 5.0% sulfuric acid 1 amino 4 anilino anthraquinonegreen shade.

EXAMPLE 4 A one-pound package ,of the sewing thread of Example 1 is dyed in the circulating machine adapted for pressure work. The dyebath composition is as follows:

3.0% of the quinoline dye of C. I. 802

1.5% of the red acid dyeof C. I. 17.6

9.0% of the blue acid dye of sodium-.1 -amino-4'anilinoanthraquinone-2-sulfonate 6.0% copper sulfatedHzO 10.0% furfural 5 .O% sulfuric acid The dyebath is prepared following the general directions of Example 1 The package is dyed for lhour at 250* F. It is thenrinsed-and soaped at F. This is followed by ,a second rinsintg and rying. The resulting package lsobserved to. be 0 a level, deep black shadeshavmg excellent light-fast and crocking characteristics.

EXAMPLE 5 EXAMPLE 6 The procedure of Example 3 is repeated employing a dyebath of the following composition:

8.0% of the black acid dye of C. I. 304 6.0% copper sulfate- SHzO 10.0% furfural 5.0% sulfuric acid The resulting black dyeing showed excellent light-fast and alkallne perspiration resistance characteristics.

EXAMPLE 7 The process of Example 6 is repeated employing a one-pound package of polyacrylonitrile raw stock with a draw ratio of 4X. A product of similar dye characteristics to that described in Example 6 is obtained.

EXAMPLE 8 The process of Example 6 is repeated using only 5.0% furfural. A good, level, black shade is produced.

EXAMPLE 9 The process described in Example 7 is repeated using only 5.0% furfural. A good, level, black shade is produced.

Examples 10 to 24, inclusive, are listed in Table I and are cited to demonstrate applicability of the process using a variety of dyes upon yarns of different draw ratios under various conditions of pH and temperature. the dyeings are made upon Z-gram skeins of polyacrylonitrile sewing thread in glass pressure tubes. Each dyemg 1s made over a period of one hour, at temperature, in 40 cc. of bath. In addition to the dyes indicated, each bath contains 5.0% copper sulfate-SHzO, 10.0% furfural and sufficient acid toobtain the initial pH value indicated. In every case, the product is observed to be of a very bright, strong, level shade.

Table l Draw Initial F. Temper- Dye Exampk Ratio pH ature (2%) 8X 1. 5 250 A 8X 1. 5 250 13 8X 1. 5 250 8X 1. 250 D 8X 3. 0 250 A 8X 4. 0 250 'A 8X 5.0 250 A 8X 1. 5 225 A 8X 1. 5 225 B 8X 1. 5 225 0 8X 1. 5 225 D 4X 1. 5 250 A 4X 1.5 250 B. 1 4X 1. 5 250 O 4X 1. 5 250 D A represents the red acid dye of C. I. 176. B represents the yellow quinoline dye of C. I. 802. 0 represents the orange acid dye of O. I. 161. D represents the orange acid dye of G. I. 151.

It 1s essential to the commercial success of the present process that a temperature considerably In excess of 212 F. be employed during the dyeing operation. Normally, temperatures at least about F. above 212 F. are suitable. The range of 240-260 F. is preferred. The rate of color absorption is less at the lower temperatures than at those within the preferred range. While it is possible to dye certain textiles following the novel, general procedure outlined, at a temperature in the neighborhood of 212 F., color absorption is usually so slow as to be commercially impracticable. This is particularly true in the case of a textile produced from a highly-drawn polymer of acrylonitrile. Temperatures appreciably higher than the preferred range lead to excesprovide from about 4 sive shrinkage of the fibers and a breakdown of both dyestufi and reducing agent.

It is essential that the dyebath be maintained acid. A pH between 1.5 and 3 is preferred. A pH lower than 1.5 is operable but is normally avoided because of corrosion difiiculties and the like. Alkali may be used to raise the pH where desired. As indicated in the examples, a pH as high as 5 is operable. It has been observed that the brightness of the dye is sacrificed at the higher pH values although corresponding dyes in the same pH value made with sodium formaldehyde sulfoxylate are noticeably duller. While the nature of the acid employed in the acidification is not critical. a mineral acid such as sulfuric is preferred. Hydrochloric is generally to be avoided due to corrosion problems. The quantity of acid is largely governed by the pH desired.

The acid colors which are particularly suitable for use in the present process are those which contain acid groups such as -S 3H -COOH, -OSO3H. The term acid colors is used to designate the commonly known group of compounds useful for the dyeing of wool.

Since the dyeings are performed in an aqueous medium, it is necessary to employ pressure equipment at elevated temperatures. In general, autogcnous pressures are sufficient. Higher pressures may be used, limited only by the strength of the applying apparatus, without deleterious effects. Any conventional process of application, sucg as package dyeing, padding and printing may be use The percentages of the various components of the dyebath may vary over a wide range depending upon the particular dye employed and the intensity of coloration desired. The percentage of furfural necessary will be governed by the amount of cuprous ion employed. Where copper salts are present in amounts to provide 0.5 to 2.5 weight percent of cuprous ion, it has been found advantageous to employ from 1% to 10% of furfural (both based on the weight of the fiber to be dyed). A copper ion strength below this range may be used for some light shades, but is generally not suitable for strong shades. Above 2.5 weight percent of cuprous ion, a dulling is observed.

While the invention is particularly of value in the dyeing of a textile produced from a polymer of acrylonitrile with a high draw ratio, it is applicable as well to such intermediate draw ratio.

Many other modifications within the spirit of the described invention will be apparent to those skilled in the art without a departure from the inventive concept.

What is claimed is.

1. A process for dyeing a textile produced from a polymer of acrylonitrile, with acid dyes, which comprises commingling the dye an the textile in an aqueous medium having a pH less than about 5 containing a copper salt in an amount sufilcient to provide from about 0.5 to 2.5 weight percent of cuprous ion and from about 1% to 10% of furfural, both based on Weight of the material to be dyed, and carrying out the dyeing at temperatures considerably in excess of 212 F., under pressure.

2. A process for dyeing a textile produced from a polymer of acrylonitrile, with acid dyes, which comprises commingling the dye and the textile in an aqueous medium having a pH of from about 1.5 to 5 containing a copper salt in an amount sufficient to provide from about 0.5 to 2.5 weight percent of cuprous ion and from about 1% to 10% of furfural, both based on weight of the material to be dyed, and carrying out the dyeing at temperatures considerably in excess of 212 F., under pressure.

3. A process for dyeing a textile produced from a polymer of acrylonitrile, with acid dyes, which comprises commingling the dye and the textile in an aqueous medium having a pH range of from about 1.5 to 3 containing a copper salt in an amount sufiicient to provide from about 0.5 to 2.5 weight percent of cuprous ion and from about 1% to 10% of furfural, both based on weight of the material to be dyed, and carrying out the dyeing at temperatures at least about 10 F. above 212 F.

4. A process for dyeing a textile produced from a highly-drawn polymer of acrylonitrile, with acid dyes, which comprises commingling the dye and the textile in an aqueous medium having a pH of from about 1.5 to 5 containing a copper salt in an amount sufficient to 0.5 to 2.5 weight percent of cuprous 5 6 ion and from about 1% to 10% offurfural, both based published by Du Pont, Wilmington, Delaware, publicly on weight of the material to be dyed, and carrying out distributed October 17, 1951, pages 3 to 7.

the dyeing at temperatures ranging from 240-260 F., prous Ion Method of Dyeing Orlon Acrylic Fibers under autogenous pressure. With Acid Dyes, pamphlet published by Du Pont, Wil- 5. The process of claim 4, wherein the polymer of 5 mington, Delaware, printed May 1951, pages 1 to 8.

acrylonitrile is polyacrylonitrile. Tech. Bulletin, vol. 7, No. 3, September 1951, publliglged by Du Pont of Wilmington, Delaware, pages 156- References Cited in the file of this patent A mer. Dyestufi Reporter for January 19, 1953. ages Developments in the Dyestufi Industry, pamphlet 10 P39-P41. 

1. A PROCESS FOR DYEING A TEXTILE PRODUCED FROM A POLYMER OF ACRYLONITRILE, WITH ACID DYES, WHICH COMPRISES COMMINGLING THE DYE AND THE TEXTILE IN AN AQUEOUS MEDIUM HAVING A PH LESS THAN ABOUT 5 CONTAINING A COPPER SALT IN AN AMOUNT SUFFICIENT TO PROVIDE FROM ABOUT 0.5 TO 2.5WEIGHT PERCENT OF CUPROUS ION AND FROM ABOUT 1% TI 10% OF FURFURAL, BOTH BASED ON WEIGHT OF THE MATERIAL TO BE DYED, AND CARRYING OUT THE DYEING AT TEMPERATURES CONSIDERABLY IN EXCESS OF 212* F., UNDER PRESSURE. 